In this process, it is required that the film be kept absolutely flat in the carrier or vacuum platen and be kept in perfect register because many different images are to be put into the same piece of film by masking. The photographer starts doing this creative work by doing it in his large format view camera. The camera must be maintained in absolute rigid placement and the carrier to be inserted into the camera must always go into the camera at the same precise location. The film that goes into the holder is in the precise location in the holder, when the holder is inserted into the camera. Because of the various areas which may be masked on the film to present other images, it is required that the film carrier be removed as many times as masking is necessary.
There are many instances that the photographer cannot complete all his imaging onto the film by just using his camer, for instance, putting in words of type or graphs or other images which he may use enlarged, or reduced. To do so he projects these images down to a vacuum platen.
The carrier film in the enlarging mode, projects down an image, and must go over a pin registration system, and where the platen is also in a fixed position since two pieces of film of the same size of which are a color film and the other one is a mask to hold back an area for each mask.
In the process of making these masks, first the mask is placed over the film to get the area that is to be blocked out. It is then made into a reversal so that an image can be placed into the correct clear area onto the film so as to receive the other image. This process is repeated for as many masks to superimpose all the images required for that completion of the special effect photography onto the film.